James Katz was a senior research physician at the National Institute of Arthritis and Musculoskeletal and Skin Diseases at the National Institutes of Health in Bethesda, Md. After hearing the patient’s story, he stepped out of the exam room to give her a chance to change into a hospital gown. As he waited, Katz considered the possibilities. When he first heard that she had joint pains that resolved with prednisone, the specialist thought that she probably had rheumatoid arthritis (R.A.). It was one of the most common inflammatory joint diseases in women her age and could sometimes affect the lungs. But she needed extremely high doses of prednisone to manage her symptoms, and that was not typically necessary for treating R.A., which was usually exquisitely sensitive to the anti-inflammatory properties of steroids. Most patients with R.A. could be managed on five to 10 milligrams of prednisone. She needed 10 times that. No, Katz decided, this was probably something else.

At the top of his new list was a rare disease formerly called Churg-Strauss syndrome, now known as eosinophilic granulomatosis with polyangiitis (EGPA). This is a disease not of the joints — like R.A. — but of the blood vessels. A vasculitis like EGPA is dangerous because the involved blood vessels can be anywhere in the body. EGPA often starts in the lungs, frequently in patients who have asthma, but can then spread throughout the body. But in EGPA, patients have high levels of eosinophils, the white cells that drive the disease. Hers were normal. And EGPA usually causes more muscle pain than joint pain. So it wasn’t a great fit.

As the doctor examined the young woman, he paid special attention to her joints. If she had any sign of inflammation there — any redness or swelling or fluid in the joint space — it would make EGPA an even less likely diagnosis. Her knees looked normal — not red, not swollen — but they were quite tender. He had her straighten her legs and then gently but firmly pressed on her right thigh, a couple of inches above the knee, and moved his hand down the leg until he reached the kneecap. The joint space of the knee extends up into the thigh, and so if there is a small amount of fluid, it can be missed unless it’s collected together at the joint. He found no obvious fluid.

He then pressed gently on the outer aspect of the knee joint. If there was any fluid there, it would show up in the only space left, as a little swelling on the other side of the knee — the so-called bulge sign. Sure enough, there it was. Interesting. There was inflammation somewhere in the joint. If it was in the outer smooth surface where the joint came together, known as the synovium, then it probably was R.A. But what if it was in the cartilage that cushioned the joint? He then pressed on a spot on her chest where cartilage connects the ribs to the breastbone. The patient jumped back in pain. “I didn’t even know it hurt there,” she exclaimed.

To Katz, these two findings suggested a very rare disorder, a disease that causes inflammation and eventually destruction of cartilage. “Do you ever have pain in your ears when you wear a hat,” he asked, “or when you sleep on your side?” The patient was amazed. No one had ever asked that question. Yes, she replied. And did her nose ever get sore or red when she wore sunglasses? Again, she was amazed. Yes. Often. What in the world could that mean? She was a doctor, a specialist in intensive-care medicine and infectious diseases, and she’d never heard of either of these symptoms.



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